Does anyone know where I can get something like a bill of materials for a typical communication satellite or something like a cost breakdown by system. I'm curious what makes really drives the price of those satellites.

Doubtful. Besides each design being different, there are many variables in cost beyond the technical. The engineering, administrative, testing, launch, and life-time operational costs are many many times more expensive than just the flight hardware.

But I am specifically interested in the flight hardware. I know there are common bus such as Lockheed A2100 or Boeing 702. While I understand there may be variations, is there an estimate of costs to within a factor of 2-3.5 for the parts?

Aerospace components are not commodity items that have set cost ranges like automotive parts. Most programs have a budget that is established by a governmental (Congress) or Executive Board(commercial telecom Co.), that is pretty much a "ball-park guess" and then that filters down into the subcontracts, and drives (inflates) costs. Very little of the hardware is COTS, and even the off the shelf stuff is subject to price negotiation and custom fitting. Which in turn is dependent upon how much leverage the purchaser has. A Boeing or LockMart gets a lot better price for a component than a Ball Aerospace etc. but everyone tries to get the maximum amount from this relatively limited market.

Without some price fixing agreement, wouldn't that be an unstable arrangement for the satellite manufacturers? Whoever could bid slightly lower would win which would drive prices down.

I guess my hypothesis that I want to explore is that communication satellites are becoming a commoditized product. As long as it works with in specs at the cost you promise, it makes no difference who makes it.

I would like to estimate the 'inflation' in price above the inherent cost of the parts - as if I were to build it myself assuming that I could do all the engineering. That was the intention of my initial query.

It's is highly unlikely that you will be able to find anyone willing to volunteer the prices paid on individual components and sub-contract work vs the actual costs of those bits. Both from the embarrassingly obscene markup, but also I am willing to bet that there is a significant range between examples.

A lot of the inflation in costs is a necessary evil, because of the very low rate of development and production of spacecraft, it takes a considerable financial incentive to keep people and companies with the relevant skills in aerospace vs.industries with more volume of work.

Communications satellites ARE becoming a commodity, or more the services they provide are. However their components and the technology supporting them aren't because it is still a very small niche market relative to other industries. It is highly lucrative, but is must more like an artisan market than a mass-marketed product. The costs and risks are such that it favors that model than say... cars, cell phones, or even aircraft.

a communication satellite replenshing is like a recieving e-mail from space to get the cost over work is definitely more than regreting for a fabrication of new and put it on a board to the orbit for meant skill.

we have to produce setelites on orbit. in space logistic is very easy, power is very cheap, and there is planty of junk that could be recyceled. if we could made an orbital 3d printer factory, and autonomus-bee like salvage bots we could produce things much faster and cheaper. even without rcycle, we could send smal rods of aluminum to the low orbit with orbital canons( much cheaper from rockets )and in orbital asambly line we coul manufacture the basic chasis and strucutres with more eficent and cheap way. only main electronic modules, people send from earth to orbit traditional ways. this this orbital assambly line soon shall be settled over moon and moon should be main base for mining, and with low gravity of moon , this mining and manufacturing plants will be much more sustainable. with this moon mining bases and orbital moon 3d printers we could assamble new unmaned colonies over all planets mineral rich, low gravity moons same infrastructures. if we coul arrange one of this bases on the moon explorotion and colonization of the solar system could hapened in 30-40 years construction program and things would change forever..